"I've made clang the default on x86 systems. There will probably be a few bumps as we work out the last kinks including a ABI issue for i386 system libraries, but the transition is expected to be fairly smooth for most users."

But the lack of support for OpenMP is a severe impediment for those like me that do HPC (I am working in a large astrophysical project, and our codes run on machines with 12 cores at least and take hours/days to complete!).